Connectors for attaching optical fibers to one another comprise a housing within which at least one connector terminus is located. Each connector terminus holds an optical fiber such that the optical fiber is in desired alignment with respect to a corresponding optical fiber in a connector terminus in the mating connector. One of the connector termini applies a spring pressure which causes the terminus to extend outwardly from the connector. The spring pressure provides a force which assures that the two mating termini abut one another with sufficient force to maintain desired alignment and contact of the optical fibers during shock and vibration and with sufficient force to mitigate Fresnel losses due to the formation of undesirable air gaps therebetween.
It is therefore desirable that each terminus extend from a connector under a spring biasing force. However, it has been found that coil springs, which wrap around a terminus in a helical configuration, are not suitable. Coil springs are not capable of providing sufficient force, e.g., approximately five pounds, which is required for proper mating of the termini. A stack of Belleville washers, centered about the terminus, are typically used to form a Belleville spring to provide the desired spring biasing force. Each Belleville washer has a surface which tapers outwardly in a radially inward direction. The stack of Belleville washers generally contains approximately eleven washers oriented such that adjacent washers face in opposite directions, so as to provide the desired spring force. Thus, when a terminus is pushed inwardly, i.e., toward the connector, the Belleville washers tend to flatten so as to provide the desired outwardly directed spring biasing force.
Because of the small size of each terminus, Belleville washers having a diameter of approximately {fraction (1/10)} of an inch are necessary. As can be appreciated the handling of such small washers during assembly of the terminus is extremely difficult and time consuming. The individual Belleville washers must be painstakingly stacked about the terminus, one atop another, to form a spring. Not only is it difficult to pick up and handle such small washers one at a time, as is necessary during the stacking process, but it is also difficult to ascertain the orientation of each washer (to determine which side of the washer has the tapering surface). Further, it is necessary that such assembly be done using a microscope.
As such, it is desirable to provide a spring biasing mechanism which is not subject to the handling and assembly difficulties associated with the formation of a stack of Belleville washers.
Unitary construction springs are provided for spring biasing each fiber optic terminus of a connector outwardly, so as to assure that it abuts a corresponding terminus of a mating connector with sufficient force for maintaining proper contact when exposed to shocks and vibrations. A first embodiment spring has an annular construction defining an annular inwardly extending channel having two legs and a convex web therebetween. The two legs extend radially inward from the web. Each leg defines an annular flange. Externally, the convex web defines an annular concavity. When axially compressed, the annular flanges are flexed inward and provide an axial force as they try to extend outward to regain their original position. The convex web also allows for some axial compression of the spring and thereby also generates a spring force.
Optionally, the spring may be configured to have a split-ring construction such that it is insertable over the terminus probe without having to be slid over the end thereof. In other words, the spring may comprise a discontinuity or split formed along its length allowing the spring to be opened up so as to allow it to receive the terminus probe through the split thereof.
An optional retaining ring may be utilized to maintain the spring in position about the terminus and to prevent the accidental disengagement of the spring from the terminus. The ring is fitted in surrounding relationship to the annular spring and is preferably fitted within the concavity defined on the outer surface of the web. The retaining ring should preferably be a split ring such that it may be easily fitted over the annular spring.
An alternative embodiment of the unitary construction spring of the present invention is also of annular construction and comprises a cylindrical body having an edge beveled radially inward and a longitudinal split spanning the length of the spring. In operation the spring is pushed against a stop member on the terminus causing the spring beveled edge to ride against the stop member and the spring to radially expand about the split. The spring generates a spring force as the spring attempts to regain its original position and the beveled edge cams the spring against the stop member.
Another embodiment spring of the present invention comprises a generally cylindrical body having a plurality of pairs of cut-outs which define a plurality of deformable beams which deform so as to provide a spring action. This embodiment spring is formed by taking a hollow cylinder and cutting a series of first and second diametrically opposed pairs of cut-outs through the cylinder body. The first pairs of cut-outs are oriented at 90xc2x0 with respect to the second pairs of cut-outs, thus defining the plurality of beams which bend when compressive force is applied to the spring. Each pair of cut-outs are preferably parallel to a plane perpendicular to the longitudinal axis of the cylinder. Moreover, to provide sufficient flexibility to the xe2x80x9cbeamsxe2x80x9d each cutout of each pair spans a major portion of half of the cylinder periphery.